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On the Noise Performance of a Magnetic Phonograph Pickup

The thermal noise of a magnetic phonograph pickup has been studied in detail. The analysis has been made using computer-aided design techniques employing a new empirical model of the electrical impedance. Two types of pickups are considered. The frequency spectra and the total rms value of the thermal noise have been studied, and the factors which are taken into account are the value of the load capacitance, the load resistance, the RIAA equalization, and subjective weighting according to the IEC 268-1 standard A curve. The noise performance of the pickup when used in a phonograph amplifier system has also been studied. It was found that with a preamplifier using modern semiconductor devices it is possible that the pickup can contribute as much as twice the noise voltage compared with the semiconductor devices alone. Attention should thus be placed on the noise performance of the pickup when considering the overall noise performance of a phonograph system.